Metropolitan Low-Level Outburst Incident … 19 June 2013 Wollongong Outburst Seminar Master...
Transcript of Metropolitan Low-Level Outburst Incident … 19 June 2013 Wollongong Outburst Seminar Master...
Wednesday 19 June 2013
Wollongong Outburst Seminar
Master Builders Club
Metropolitan Low-Level Outburst Incident
Learnings and Improvements
Ian Moore
Manager of Mining Engineering
Metropolitan Coal
Presentation Overview
● Metropolitan Coal
● The Incident
● Improvements in our Outburst Management Processes
● Learnings for Peabody Australian Platform and the
Illawarra Coal Industry
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● This year Metropolitan Mine turned 125
years old
● The mine has a long and proud mining
history in the Illawarra
● Peabody acquired Metropolitan in 2006
when it recognised the potential of the
operation and the direction of coal prices
● Peabody has invested $450 million to date
Metropolitan History – 125 Years Old
Metropolitan – Low-level Outburst Location
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MG 23 B hdg 6-7 c/t – 17 October 2012 @ 11.30am
Incident Sequence of Events
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EVENT No abnormal gas levels when
mining through fault zone in A Hdg
1. During bolting cycle the face slumped in at commencement of fault zone MG23 6-7ct. Approximately 5t of coal was displaced.
2. Pocket of CO2 Released exposing 5 operators to > 1.99% (Maximum reading on miner sensor)
3. Operators withdrew immediately to fresh air, minimal exposure, no harm. Withdrawal was trigged by the readout of the onboard CO2 monitor.
4. Incident scene isolated by Deputy. Undermanager & M.O.M.E. notified.
5. Outburst review committee inspected the incident scene.
6. PTM revoked by M.O.M.E.
7. Inspectorate notified - CMHSR Cl 56 (1) g Gas accumulation, withdrawal of men.
8. Drill rig mobilized to commence coring for gas content determination at face.
Rise in Gas Levels Prior to the Incident
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Panel Return Gas Readings
Increased CO2 trend
Spike at time of incident
1pm 5pm 9pm 1am 5am 9am 1pm
Increase was
observable
but relatively
small in
magnitude
(0.16%)
Contributing Factors
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1. Cross drainage hole in the fault
zone incomplete due to boggy
(soft coal) conditions
2. Permit to mine issued based on
flank passed core result.
3. No gas issues when mining
through fault in adjacent
roadway (A Hdg)
4. Historical data of the mining
through the fault zone not
reviewed (as not previously
identified as a risk at
metropolitan)
FACTORS
Core Results (90% CO2)
9.37 7.70
6.02 13.07
Failed Cores
from Additional
Re-drilling
Post Incident Sequence
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Inspection of Incident scene with Inspector of Coal mines and
Site Check Inspector
Area had been cleaned and supported to the face. Evidence
of outburst indicators
Incident re-classified as Cl 55 “low-level outburst”
Clause 51 notice served – Prohibition further mining MG23
B 6-7ct
Drill cores verified high in-situ CO2 content
High intensity drilling regime initiated in face zone
Unsuccessful in reducing insitu gas content to threshold levels
Risk assessment conducted on grunching through outburst zone
Reviewed grunching procedures and training packages
Setup panel for grunching. Spiled (pre-supported) roof level with
4m tendons
Successfully grunched through zone without incident. No
outburst triggered during shot firing
Recommenced normal mining with 30MB. Unit was off-line for 6
weeks due to incident
POST INCIDENT EVENTS
Learnings and Improvements – Changed Definition of Outburst in Metrop O.M.P.
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Previous Definition New Definition
“A violent ejection of gas, coal
and/or stone from a mining face.
Typically the volume of gas released
is significantly higher than can be
accounted for by the gas content of
the coal displaced.”
“A sudden release of gas and
material from the working place that
can vary in magnitude and intensity.”
Quoted from MDG1004
Improvements to the Metropolitan Permit to Mine
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Geological Review Added
Mandatory Attendees Added
Re-Evaluation of Panel Gas Monitoring TARP’s
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Level 2 Trigger
Level 1 Trigger
Average Background Levels
Utilising our
gas
monitoring
to record
and alarm
increasing
CO2 levels
Improvements to On-Board Gas Monitoring and Warning System
● Prior to event
– CO2 remote display partially hidden behind cover
– CO2 warning strobe not visible to off drivers side
● Changes made following event
– CO2 remote display relocated to be more visible
– CO2 warning strobe mounted on top of cover and can now be
seen from both sides of the miner
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Improvements to On-Board Gas Monitoring and Warning System
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Visibility of Gas Levels to Face Crew
Strobe for CO2 and CH4
warning relocated to roof of
display cabinet.
Relocated display readouts
(Methane – Top , Carbon Dioxide – Bottom)
CH4
CO2
Improvements to On-Board Gas Monitoring and Warning System
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Visibility of Gas Levels to Face Crew
View of strobe from off drivers
side platform
Education and Training of Workforce
Improvements to Drilling and Coring Practices
● Fan pattern – designed to suit environment
● Flank holes must close the “Grid”
● Sampling at maximum 60m spacing in worst case
location for gate roads
● Sampling every 10m on both sides of roadway in
outburst prone areas
● 4” drainage hoses from stand-pipes - increase flow rate
● Gas flow readings on every hole once every 2 weeks to
monitor reduction in gas reservoir
● Sampling between and in proximity to identified fault
zones
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Evolution of Metropolitan Cross Drainage Drilling Pattern
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Generation 1 - January 2008 Focus on Coring
Evolution of Metropolitan Cross Drainage Drilling Pattern
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Generation 2 – October 2010, Flankholes Introduced
Evolution of Metropolitan Cross Drainage Drilling Pattern
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Generation 3 – November 2011, Extended Drilling Beyond Planned Roadway, optimized drilling direction
Hole Spacing 20m Drainage 15-20m beyond roadway
Evolution of Metropolitan Cross Drainage Drilling Pattern
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Current – Holes Further Extended Beyond Planned Roadway and Spacing is Reduced in Outburst Risk Zones
Hole Spacing 10m Drainage 35-40m beyond roadway
Geological Learnings Post Incident
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Mapping Of Outburst Prone Areas
Key Learnings
● Classic definition of an outburst is now redefined
– An outburst does not have to be violent in nature
● Prediction of structures
– Outburst prone zones shaded on the mine plan to pre-determine
adequate drilling and coring patterns
– Abnormalities detected during drilling are logged
– Cuttings are reviewed by Geologist for Geotech assessment
– Geological information to be thoroughly reviewed at the PTM
meeting. Geotech submits a report at every PTM
● Review all historical outburst incidents at Metropolitan
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Key Learnings for Peabody and the Coal Industry
Key Learnings
● An educated workforce is a more confident, safer and
productive workforce
● Compliance core regime around structures is critical
● Photos of incident scene - poor quality
– Training of management in underground photography completed
● The improvements to the Outburst Management
Processes has lowered Metrop’s Outburst Risk profile
and improved drivage rates
– Record development metres achieved in May 2013 with
enhanced compliance requirements
● Learning’s and knowledge of Outburst risk shared on the
Peabody Platform and the Illawarra UG coal mines
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Key Learnings for Peabody and the Coal Industry
Importance Of Sharing Key Learnings
Metropolitan’s sister Longwall mine in Qld
● North Goonyella
– Very Gassy
– 420 m deep
– Operating under Outburst Management Plan
● Recently had a similar outburst associated with
structures and coring regime
● Peabody instantly directed sharing of learnings,
information and Management Plans between sites and
operations personnel flew interstate to ensure our
knowledge base was utilised to full potential.
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QUESTIONS ?